Today, CT and other imaging modalities (e.g., mammography, digital radiography, etc.) are useful to provide information, or images, of interior aspects of an object under examination. Generally, the object is exposed to radiation (e.g., X-rays, gamma rays, etc.), and an image(s) is formed based upon the radiation absorbed and/or attenuated by the interior aspects of the object, or rather an amount of radiation photons that is able to pass through the object. Typically, highly dense aspects of the object (or aspects of the object having a composition comprised of higher atomic number elements in the case of dual-energy) absorb and/or attenuate more radiation than less dense aspects, and thus an aspect having a higher density (and/or high atomic number elements), such as a bone or metal, for example, will be apparent when surrounded by less dense aspects, such as muscle or clothing.
Radiation imaging modalities generally comprise, among other things, one or more radiation sources (e.g., an X-ray source, Gamma-ray source, etc.) and a detector array comprised of a plurality of pixels that are respectively configured to convert radiation that has traversed the object into signals that may be processed to produce the image(s). As an object is passed through an examination region defined between the radiation source(s) and the detector array, radiation is absorbed/attenuated by the object, causing changes in the amount/energy of radiation detected by the detector array.
It is desired to detect most, if not all, of the radiation that passes through the object (e.g., to produce a higher fidelity image). However, only a portion of the X-ray dose passing through the object is detected or measured by the detector array due to the presence of cross-talk inhibiting reflective material located between adjacent scintillators of the detector array, where radiation that impinges upon the reflective material goes undetected or unmeasured. It is not uncommon for 25% to 35% of the radiation that passes through the object to impinge upon the reflective material (e.g., instead of the active/scintillator material) and thus go undetected.
Moreover, in some applications (e.g., security) it is also beneficial to obtain an effective atomic number (Zeff) of objects scanned by a radiation system. Zeff is a material property that allows threat materials to be distinguished from benign materials (e.g., by providing a metric to differentiate objects having similar density characteristics). X-rays having more than one distinct X-ray spectra (e.g., corresponding to more than one distinct photon energy) are used to measure Zeff (e.g., where photons of different energies are attenuated differently by the same material to yield an indication of a characteristic of the material). While some detector arrays are configured to detect two distinct photon energies, such as detector arrays that implement photon counting technologies and/or sandwich technologies (e.g., that have multiple layers of scintillator materials), such detector arrays are generally costly and/or complex.